class Solution {
    public void duplicateZeros(int[] arr) {
        int n=arr.length;
        int dest=-1,cur=0;
        while(cur<n){
            if(arr[cur]!=0) 
                dest++;
            else
                dest+=2;
            if(dest>=n-1) 
                break;
            cur++;
        }
        if(dest==n){
            arr[n-1]=0;
            dest-=2;
            cur--;
        }
        while(cur>=0){
            if(arr[cur] == 0){ 
                arr[dest--] = 0;
				arr[dest--] = 0;
				cur--;
            }else
                arr[dest--] = arr[cur--];
        }
    }
}